Polyadenylation of ribosomal RNA by Candida albicans

Candida albicans is the leading fungal pathogen in immunocompromised patients such as those with AIDS and malignancies. It is a polymorphic organism existing as a unicellular yeast or as filamentous forms that include pseudohyphae and true hyphae. While studying the early period of hyphal transformation, comparing cDNAs from yeast to those in early transition, we were surprised to find 25S rRNA represented frequently in our differential display assays, suggesting that our reverse transcription with poly-T primers was copying rRNA with extended poly-A 3' ends. We now report that both the yeast forms and germinating organisms polyadenylate some of their 25S rRNA transcripts. We also found a rapid and transient enhancement of this process upon stimulation with serum. These data indicate that 25S rRNA polyadenylation is part of the biological repertoire of C. albicans and its transient upregulation just prior to hyphal development raises the possibility of a regulatory role in this transition.